Nebulizer apparatus and method

ABSTRACT

An apparatus and method for providing a nebula or aerosol to a patient. In one aspect, a nebulizer is pressure sensitive so that nebulization is coordinated with a breathing cycle of the patient. The nebulizer includes a movable gas diverter that diverts pressurized gas across a liquid outlet. The diverter is moved in response to the patient&#39;s breathing cycle. In one aspect, a biasing member moves the diverter. According to another aspect of the nebulizer, an annular liquid orifice disperses an aerosol in a radial direction in response to a pressurized gas flow from an orifice located concentrically thereto. Multiple liquid orifices may be provided. In a further aspect of the nebulizer, a reservoir includes an upper, wide portion and a lower narrow portion to apply relatively uniform pressure at a liquid orifice.

BACKGROUND OF THE INVENTION

[0001] The present invention relates to a method and apparatus fordelivering an aerosol, nebulized liquid or solid medicine or a vapor toa patient's respiratory tract, and more particularly, the presentinvention relates to an improved nebulizer that provides an aerosol moreefficiently and with improved particle size uniformity.

[0002] Medical nebulizers for generating a fine spray or nebula of aliquid medicine that can be inhaled by a patient are well known devicescommonly used for the treatment of certain conditions and diseases.Nebulizers have applications in treatments for conscious,spontaneously-breathing patients and for controlled ventilated patients.

[0003] In some nebulizers, a gas and a liquid are mixed together anddirected against a baffle. As a result, the liquid is aerosolized, thatis, the liquid is caused to form into small particles that are suspendedin the air. This aerosol of the liquid can then be inhaled into apatient's respiratory tract. One way to mix the gas and liquid togetherin a nebulizer is to pass a quickly moving gas over a liquid orifice tipof a tube. The negative pressure created by the flow of pressurized gasis a factor that contributes to drawing the liquid out of the liquidorifice tip into the stream of gas and nebulize it.

[0004] Some of the considerations in the design and operation ofnebulizers include regulation of dosages and maintenance of consistentaerosol particle size. In conventional nebulizer design, pressurized gasmay entrain a liquid against a baffle on a continuous basis until theliquid in a reservoir is depleted. Continuous nebulization may result ina waste of aerosol during a patient's exhalation or during a delaybetween a patient's inhalation and exhalation. This effect may alsocomplicate regulation of dosages because the amount of wasted aerosolmay be difficult to quantify. Also, continuous nebulization may affectparticle size and/or density. In addition, there may be excessmedication lost to condensation on the nebulizer or mouthpiece duringperiods of non-inhalation. On the other hand, interrupted nebulizationmay also affect particle size and density as the nebulization is turnedon and off.

[0005] There are several other considerations that relate to theeffectiveness of nebulizer therapies. For example, it has been suggestedthat nebulization therapy is more effective when the generation ofaerosol particles is relatively uniform, for example, producingparticles of a particular size, particles within a range of sizes,and/or particles a substantial percentage of which are within a range ofsizes. One particle size range that has been considered to beappropriate for inhalation therapy includes a particle size range ofapproximately 0.5 to 2 microns. Other particle size ranges may besuitable or preferable for particular applications. Generally, large andsmall size droplets should be minimized. It has also been considereddesirable for some inhalation therapies that a substantial percentage,e.g. over 75%, of the aerosol particles be less than approximately 5microns depending on the desired area of particle deposition in therespiratory tract. In addition, it may be advantageous for a nebulizerto be able to generate a large amount of aerosol quickly and uniformlyso that a proper dosage can be administered.

[0006] Accordingly, with these considerations taken into account, thereis a need for an improved nebulizer.

SUMMARY OF THE INVENTION

[0007] The present invention provides a method and apparatus fordelivering nebulized liquid or solid medication or vapor to a patient.According to one aspect, the present invention includes a nebulizer thatgenerates an aerosol during inhalation, and sometimes during bothinhalation and exhalation, and that can be used both by ventilatedpatients and spontaneously breathing patients.

[0008] According to another aspect of the invention, there is provided anebulizer that is pressure sensitive so that nebulization is coordinatedwith a natural physiological cycle of the patient, such as the patient'sbreathing cycle. The nebulizer includes a movable gas diverter thatdiverts pressurized gas across a liquid outlet. The diverter is moved inresponse to the patient's breathing cycle. In one embodiment, a biasingmember such as membrane, moves the diverter.

[0009] According to still another aspect of the invention, a nebulizeris provided having an annular liquid orifice that disperses an aerosolin a radial direction in response to a pressurized gas flow from a gasorifice located concentrically thereto.

[0010] In yet another aspect of the invention, a nebulizer is providedhaving a chamber with multiple liquid orifices and/or gas orificeslocated therein. The multiple orifices may be annular orifices. Adiverter may be provided to direct gas across the multiple liquidorifices.

[0011] In a further aspect of the invention, a nebulizer reservoirincludes an upper, wide portion and a lower narrow portion to applyrelatively uniform pressure at a liquid orifice that draws liquid fromthe reservoir.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012]FIG. 1 is a partial cross-sectional side view of a firstembodiment of a nebulizer according to the present invention.

[0013]FIG. 1A is a cross-sectional view of the nebulizer of FIG. 1 shownin an inspiration cycle.

[0014]FIG. 2 is a cross-sectional view of the nozzle assembly of thenebulizer of FIG. 1.

[0015]FIG. 3 is a cross-sectional top view of the nebulizer of FIG. 1taken along line 3-3′ (without the baffle for clarity).

[0016]FIG. 4 is perspective view of the top portion of the nebulizer ofFIG. 1.

[0017]FIG. 4A is perspective view of the top of the nebulizer shown inthe inspiration cycle of FIG. 1A.

[0018]FIG. 5 is a cross sectional view of a second embodiment of thenebulizer of the present invention.

[0019]FIG. 6 is a cross sectional view of the bottom of the chimney ofthe embodiment of FIG. 5.

[0020]FIG. 7 is a cross sectional view similar to FIG. 6 showing analternative embodiment the bottom of the chimney of the nebulizer shownin FIG. 5.

[0021]FIG. 8 is a cross-sectional view of a portion of the nebulizer ofFIG. 5 showing the diverter ring.

[0022]FIG. 9 is a cross sectional view similar to FIG. 8 showing analternative embodiment of the diverter ring arrangement for theembodiment of the nebulizer of FIG. 5.

[0023]FIG. 10 is a cross sectional view similar to FIG. 8 showinganother alternative embodiment of the diverter ring arrangement.

[0024]FIG. 11 is a cross sectional view of a third embodiment of thenebulizer of the present invention.

[0025]FIG. 12 is a top view of the embodiment nozzle assembly of FIG.11.

[0026]FIG. 13 is a cross sectional view of the embodiment of FIG. 11taken along line 13-13′.

[0027]FIG. 14 is a cross sectional view of a fourth embodiment of thenebulizer of the present invention.

[0028]FIG. 15 is a cross sectional view of a fifth embodiment of thenebulizer of the present invention.

[0029]FIG. 16 is a cross sectional view of a sixth embodiment of thenebulizer of the present invention.

[0030]FIGS. 17A and 17B shows cross sectional views of a seventhembodiment of the present invention.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS

[0031] I. First Embodiment

[0032] A first preferred embodiment of a nebulizer 10 is illustrated inFIG. 1. The nebulizer 10 is a small volume nebulizer and includes ahousing or container 12 defining an internal chamber 14. The housing 12is formed of a cylindrically-shaped side wall portion 18, a top portion20, and a bottom portion 22. The component parts of the housing 12 maybe formed of separate, multiple pieces of material that are connectedtogether by welding, adhesives, etc., or more preferably, some of thecomponent parts may be formed together of a single piece of materialformed by an injection molding process. For example, the bottom, andside portions 22 and 18 may be formed of separate pieces that areconnected together, or preferably, these parts may be formed of onepiece of molded plastic. Any of a number of plastics may be suitable,including polycarbonate, or polycarbonate blends. A cover 21 isremovably mounted on the upper portion of the housing 12, such as bymeans of a snap-on cover arrangement, twist-lock threads, screws orother types of fasteners. The housing 12 is approximately 6 cm (2.36 in)in height and has a diameter of approximately 4 cm (1.57 in).

[0033] A lower portion 23 of the chamber 14 serves as a reservoir forholding a fluid 25 for nebulizing, such as a solution containing amedication. Located in the lower portion 23 of the housing 12 is anozzle assembly 24. Referring to FIGS. 1-3, the nozzle assembly 24extends downward from the chamber 14 of the housing 12 to a fitting 28located external of the chamber 14 on a bottom side 22 of the housing12. The fitting 28 is sized to connect to a supply 27 of pressurized gasprovided through conventional tubing 29. The pressurized gas may besupplied by any suitable source, such as a conventional gas supply usedin hospitals, a pump, compressor, cartridge, canister, etc.

[0034] The nozzle assembly 24 is comprised of an outer tubular member 30and an inner tubular member 32. The inner tubular member 32 has apassageway 34 that extends from an opening 36 in the bottom end of thefitting 28 to a gas outlet orifice 38 located at a top end 39 of thenozzle assembly 24. The inner tubular member 32 is located in an innerpassageway 40 of the outer tubular member 30. The inner tubular member32 is sized to slide into the inner passageway 40 of the outer tubularmember 30 so that it is aligned therein. A passageway 42 is formed bygrooves or slots on the outer surface of the inner tubular member 32and/or the inner surface of the outer tubular member 30. The passageway42 extends from an opening 44 located at the reservoir 23 of the lowerportion of the chamber 14 to a liquid outlet orifice 46 located at thetop end 39 of the nozzle assembly 24. The passageway 42 serves to conveyliquid medicine from the reservoir 23 at the bottom of the chamber 14 tothe liquid outlet orifice 46 at the top of the nozzle assembly 24. (Inan alternative embodiment, the passageway 42 may be formed by spaces orregions between fins located on the outer surface of the inner tubularmember 32 and/or the inner surface of the outer tubular member 30.)

[0035] As shown in FIG. 3, the liquid outlet orifice 46 has an annularshape defined by the top ends of the outer tubular member 30 and theinner tubular member 32 of the nozzle assembly 24. The gas outletorifice 38 has a circular shape and is located concentrically of theannular liquid orifice. In one embodiment, the gas outlet orifice 38 isapproximately 0.022 inches in diameter and the liquid outlet orifice 46has an outer diameter of approximately 0.110 to 0.125 inches and aninner diameter of approximately 0.084 inches. These dimensions areprovided by way of example and the nebulizer may be made in other sizeswith different dimensions as desired.

[0036] The top end 39 of the nozzle assembly 24 is formed by the topends of the outer and inner tubular members 30 and 32. In a presentembodiment, the top end 39 is a generally flat surface having a diameterof approximately 0.18 inches. In alternative embodiments, the top end 39may have an other-than-flat shape, for example, the inner tubular member32 may be spaced above the outer tubular member 30 so that the liquidorifice 46 is located below the gas orifice 38.

[0037] The nozzle assembly 24, or a portion thereof, may be formed aspart of the housing 12 as a single piece of material in an injectionmolding process. For example, the inner tubular member 32 may be formedof the same piece of injected molded plastic as the bottom of thehousing 12.

[0038] Referring again to FIG. 1, the nebulizer 10 also includes achimney assembly 50. The chimney assembly 50 is located in an upperportion of the chamber 14 above the liquid reservoir 23. The chimneyassembly 50 includes a tubular body 51 that defines an internalpassageway 52 that extends from an inlet opening 56 in the housing cover21 to an outlet opening 58 at a bottom end of the tubular body 51. Thus,the chimney assembly 50 serves as an inlet channel for ambient air toenter into the chamber 14. The inlet opening 56 communicates withambient air (through ports of an actuator button, as described below)and the outlet opening 58 communicates with the chamber 14.

[0039] Located on the lower end of the chimney assembly 50 is a diverter60. The diverter 60 may be formed of the same piece of molded plasticmaterial as the chimney 50 or alternatively, the diverter 60 may beformed of a separate piece of material that is attached by suitablemeans to the rest of the chimney assembly 50. (The diverter may also beprovided pneumatically, for example by an opposing gas source locateddirectly 19 opposite the nozzle.) The diverter 60 is located directlyopposite from the gas outlet orifice 38 and the liquid outlet orifice 46located at the top end 39 of the nozzle assembly 24. The diverter 60 ismovable SO that the distance between the diverter 60 and the top surface39 of the nozzle assembly 24 can be varied. The diverter 60 has of aflat circular shape with a diameter of approximately 0.18 inches so thatit extends over both the gas and liquid orifices 38 and 46 out toapproximately the edge of the top surface 39 of the nozzle assembly 24.

[0040] The chimney assembly 50 is connected to the housing 12.Specifically, the chimney assembly 50 is attached to the top portion 20of the housing 12 by means of a membrane or diaphragm 64. The membrane64 is a ring-shaped piece of a flexible, resilient material, such assilicone rubber. An outer rim or bead of the membrane 64 is secured in agroove in the top portion 20 of the housing 12 and/or the cover 21. Aninner rim of the membrane 64 is secured in a slot formed by two parts ofthe chimney assembly 50. The membrane 64 has a rolled cross-sectionalprofile as shown in FIG. 1. This permits the membrane 64 to act as arolling diaphragm. The membrane 64 permits limited movement of thechimney assembly 50. The chimney assembly 50 is connected to themembrane 64 so that the membrane 64 biases the chimney assembly 50 awayfrom the nozzle assembly 24 as shown in FIG. 1. When installed in themanner shown in FIG. 1, the bottom of the chimney assembly 50 isapproximately 0.15 inches away from the top surface of the nozzleassembly 24.

[0041] Located at the top end of the chimney assembly 50 is an actuator68. The actuator 68 connects to the tubular body 51 of the chimneyassembly 50 and extends through the opening 56 at the top of the housing12 in the cover 21. The actuator 68 includes a closed top side 70 withone or more side opening ports 72.

[0042] Referring to FIG. 4, located on the sides of the body of theactuator 68 are indicators 69A and 69B. The indicators 69A and 69B maybe formed of colored markings or parallel rings on the sides of theactuator 68. In a preferred embodiment, the indicator 69A is red and islocated next to the top side 21 of the nebulizer body 12. The indicator69B is preferably green and is adjacent to and above the indicator 69A.

[0043] Located in the chamber 14 at the bottom end of the chimneyassembly 50 is a bell-shaped baffle 74. The baffle 74 extends from theopening 58 at the bottom of the chimney passageway 51 outward toward theinside wall of the cylindrical portion 18 of the housing 12. The baffle74 includes a horizontal portion 75 and a vertical portion 76 thatextends downward from the horizontal portion 75 toward the top of thenozzle assembly 24. The baffle 74 has an open bottom side providing anair passageway around the bottom side of the cylindrical vertical wall76.

[0044] As mentioned above, the diverter 60 is movable relative to thenozzle assembly 24. The present embodiment provides a means to limit thetravel of the diverter relative to the nozzle assembly 24. This may beaccomplished in any of several suitable ways. In a present embodiment,the movement of the diverter 60 toward the nozzle assembly 24 is limitedby one or more stop pins 80. The stop pins 80 extend up from the bottomportion 22 of the housing. In a present embodiment, there are three stoppins. The top ends of the stop pins 80 are spaced away from the bottomend of the vertical wall 76 of the baffle 74. Because the chimneyassembly 50 is movable vertically due to its connection to the housing12 by means of the flexible membrane 64, the stop pins 80 provide alower limit to the movement of the chimney assembly 50. In a presentembodiment, the stop pins 80 are spaced so that when the lower edge ofthe vertical wall 76 of the baffle 74 is brought into contact with thestop pins 80, a space ‘h’ is provided between the diverter 60 and theupper surface 39 of the nozzle assembly 24. In a preferred embodiment,the space ‘h’ is approximately between 0.025 and 0.045 inches, or morepreferably approximately between 0.030 and 0.040 inches, and mostpreferably approximately 0.033 inches.

[0045] In alternative embodiments, movement of the diverter 60 towardthe nozzle assembly 24 may be limited by means other than stop pins. Forexample, if the housing were formed by an injection molding process,steps, shoulders, fins, or other structures, may be provided along thewalls of the housing in order to limit the downward travel of thechimney and/or diverter.

[0046] Also located in the chamber 14 is a diverting ring 82. Thediverting ring 82 is located on the inner wall of the cylindricalportion 18 of the housing 12. Specifically, the diverting ring 82 ispositioned adjacent to the baffle 74. The diverting ring 82 is sized todefine a gap 86 around the baffle 74. The diverting ring 82 serves toimpede large droplets of liquid that might form on the inner wall of thehousing 12 and divert large droplets back down into the reservoir 23 atthe bottom of the housing 12. In addition, the diverting ring 82 servesto provide a relatively tortuous path for the flow of aerosol particlesfrom the lower portion of the chamber 14 to the upper portion. Thistortuous path also serves to reduce the presence of larger particles andhelps to make the particle size distribution more uniform.

[0047] As mentioned above, the bottom of the chamber 14 serves as areservoir 23 for a liquid to be nebulized. In a present embodiment, thereservoir has a funnel-like shape to direct the liquid to be nebulizedin a downward direction toward the inlet 44. The reservoir portion ofthe chamber 14 is formed of at least two portions or stages. In apresent embodiment, an upper portion 88 of the reservoir is relativelywide having a diameter approximately the same as that of the cylindricalportion 18 of the housing 12 (e.g. 2.36 in). The upper portion 88 isrelatively shallow (e.g. 0.3125-0.25 in). The upper portion 88 of thereservoir tapers in a funnel-like manner toward a lower portion 90 (orsecondary well) of the reservoir. The lower portion 90 is relativelynarrow, but relatively deep (e.g. 0.25 in). The lower portion 90 of thereservoir is slightly wider (e.g. 0.625 in) than the outer diameter ofthe nozzle assembly 24. The opening 44 from which the liquid is drawn islocated at the bottom of the lower portion 90 of the reservoir. In apresent embodiment, the reservoir 23 also includes an intermediateportion 92 located between the upper portion 88 and the lower portion90. The intermediate portion 92 of the reservoir 23 has a height and awidth between that of the upper and lower portions.

[0048] In the embodiment of the nebulizer shown in FIG. 1, the relativesizes and dimensions of the upper, lower and intermediate portions ofthe reservoir 23 contribute to the generation of an aerosol wherein theaerosol particle size and output is relatively uniform overall. Asdescribed more below, the liquid in the reservoir 23 is drawn throughthe opening 44 and up the liquid passageway 42 in part by the negativepressure caused by the flow of gas across the liquid orifice 46. Thesuction force provided by the gas flow both draws the liquid up out ofthe reservoir to the top of the nozzle and entrains the liquid with acertain velocity in the air flow. As the liquid is nebulized, thesurface level of the liquid in the reservoir goes down, thereby directlyincreasing the distance that the liquid has to be drawn up out of thereservoir to the orifice at the top of the nozzle. As the distance ofthe top of the nozzle over the liquid surface increases, more energy isrequired to draw the liquid up to the liquid orifice at the top of thenozzle assembly 24. Assuming a relatively constant gas pressure, thisincreasing distance may have the effect of decreasing liquid flowthrough the liquid orifice which in turn may affect the uniformity ofthe aerosol particle size and rate.

[0049] The embodiment of the nebulizer in FIG. 1 reduces this possibleadverse effect. With the embodiment of FIG. 1, a relatively largeportion of the liquid is stored in the upper portion 88 of the reservoirand a relatively smaller portion of the liquid is stored in the lowerportion 90 of the reservoir. Since the large portion 88 of the reservoiris wide and relatively shallow, the surface level of the liquid in thereservoir changes relatively slightly as the liquid in this portion ofthe reservoir is drawn down. Therefore, there is little change in theenergy needed to draw this amount of liquid up from the reservoir to theliquid orifice 46 as this portion of the liquid is depleted. When allthe liquid in the upper portion 88 of the reservoir is nebulized, theremaining liquid in the lower portion 90 of the reservoir is drawn intothe liquid passageway 42 and the height of the top surface of the liquidfalls rapidly. However, since the lower portion 90 of the reservoir isrelatively narrow, it contains only a small portion of the liquid beingnebulized so there is relatively little overall effect on aerosolparticle size and output from this portion of the liquid.

[0050] Another advantage provided by the funnel shape of the reservoiris that the relatively narrow size of the lower portion 90 of thereservoir has less surface area thereby directing the liquid toward theopening 44. This causes most or all of the liquid to be directed toopening 44 with little waste.

[0051] The nebulizer 10 of FIGS. 1-3 may also include a sensor 89. Thesensor 89 may be attached to the housing 12 at any suitable location,such as on the cover 21, as shown in FIG. 1. The sensor 89 monitors theoperating cycles of the nebulizer 10. The sensor 89 may monitoroperating cycles by monitoring the movement of the chimney portion 50relative to the housing body 12. The sensor 89 may utilize any suitabletechnology, such as electronic, pneumatic, or mechanical. For example,the sensor may be responsive to a change in local capacitance as thechimney moves closer and further from the top of the housing.Alternatively, the sensor may be responsive to a embedded magnet, or maymeasure an optical parameter, etc. The sensor 89 monitors the cycles ofoperation and provides a count that can be observed by the user or amedical care provider. This enables the user or care provider toestimate how much medication has been delivered. The sensor 89 includesa display or similar device for this purpose. In addition, the sensormay also include appropriate programming to report on the duration,frequency, speed, etc. of nebulizer operation. These parameters may alsobe provided to inform the patient or care provider about the delivery ofmedication. This embodiment of the nebulizer may also includeappropriate programming to limit the amount of medication or drugs thatcan be administered. For example, if the nebulizer is used to deliverdrugs for pain control, such as morphine, the nebulizer can beprogrammed to limit the amount of such drugs that can be delivered tothe patient.

[0052] The embodiment of the nebulizer shown in FIGS. 1-3 is adapted foruse by a spontaneously breathing patient, so the aerosol from thenebulizer is output to a mouthpiece or mask that can be used by thespontaneously breathing patient. Accordingly, located in an upperportion of the chamber 14 is an adapter 99 having an outlet 98 thatconnects to a mouthpiece 100. In alternative embodiments, as describedfurther below, the nebulizer may be used with ventilator systems andinstead of the mouthpiece 100, the adapter 99 would connect the outlet98 to the ventilator circuit.

[0053] To operate the nebulizer 10, a suitable amount of a liquid suchas a medicine or water is placed in the reservoir of the chamber 14. Theliquid may be placed in the reservoir by first removing the cover 21,membrane 64, and chimney 50, filling an appropriate amount of liquidinto the reservoir, and replacing the cover 21, membrane 64, and chimney50 onto the housing 12. In a preferred embodiment, the cover, membraneand chimney are assembled together and would be removable together as aunit. (Alternatively, the liquid may be placed into the reservoirthrough the mouthpiece 100, or further, the nebulizer may be providedpre-filled with the appropriate amount of medicine from themanufacturer, or in yet another alternative, the nebulizer may beprovided with a resealable fill port.) The source of pressurized gas 27is connected to the fitting 28. The source of pressurized gas 27 may bean external source that provides gas at a rate of 4 to 10 liters perminute in a range from 35 p.s.i to 50 p.s.i, although other rates andpressures could also be suitable. Gas is delivered through thepassageway 34 and is expelled from the gas outlet orifice 38 into thechamber 14. However, at this stage, prior to inhalation by the patient,the gas travels upward from the gas outlet orifice 38 and nebulizationdoes not occur since the diverter 60 is in the non-nebulizing position.The membrane 64 holds the chimney assembly 50, including the diverter60, away from the nozzle 24. When in the non-nebulizing position, thedistance between the diverter 60 and the top of the nozzle isapproximately 0.15 inches. At this distance, the gap between thediverter 60 and the nozzle 24 is such that the flow of gas does notcreate sufficient negative pressure over the liquid orifice 46 to drawout the liquid.

[0054] To generate an aerosol with the nebulizer, the patient places themouthpiece 100 to his/her mouth. When the patient inhales, air iswithdrawn from the chamber 14 reducing the pressure inside the housing12. The lower pressure in the chamber 14 causes the membrane 64 to flexdrawing the chimney 50 down. The lower position of the chimney 50 isshown in FIG. 1A. Downward movement of the chimney 50 is limited by thestop pins 80. When the stop pins 80 limit the downward movement of thechimney 50, the diverter 60 is spaced a predetermined distance ‘h’ fromthe top surface 39 of the nozzle assembly 24. In a present embodiment,the gap ‘h’ is approximately 0.033 inches.

[0055] The pressurized gas, which may be continuously injected into thenebulizer through the fitting 38, is diverted sideways approximately 90°by the diverter 60. Since the gas outlet orifice 38, diverter 60 andnozzle top 39 are generally circular, gas exiting the orifice 38 isdispersed evenly in an approximately 360° or radial pattern. The liquidmedicine in the reservoir is then drawn up the passageway 42 and out ofthe liquid outlet orifice 46 in part by the negative pressure caused bythe moving gas passing over the liquid outlet orifice. The liquid drawninto the diverted gas stream is aerosolized at least by the time itreaches the larger volume space of the chamber. In a present embodiment,the liquid medicine drawn out of the liquid orifice 46 has little or noimpaction against the diverter 60. However, in an alternativeembodiment, the liquid drawn into the gas stream may be directed againstthe diverter 60.

[0056] As the liquid is nebulized it travels into the chamber 14 along apath around the lower edge of the baffle 74. As the patient inhales, thenebulized liquid travels upward through the gap 86 between the baffle 74and the diverting ring 82, and out through the mouthpiece 100 to thepatient's respiratory tract.

[0057] When the patient ceases to inhale, the pressure in the chamber 14rises. The biasing of the membrane 64 is again sufficient to move thechimney 50 upward, increasing the distance between the diverter 60 andthe top surface 39 of the nozzle assembly 24, and causing nebulizationof the liquid to cease. In alternative embodiments, a spring, pneumaticvalve, or other biasing device may be utilized, alone or in combinationwith each other and the membrane, to move the diverter 60 into anon-nebulizing position. Thus, the nebulizer automatically cyclesaerosol generation in time with the breathing cycle of the patient.

[0058] If the patient exhales into the nebulizer, no nebulization occurssince the diverter 60 is in the non-nebulizing position due to thebiasing of the membrane 64. Upward travel of the chimney 50 is limitedby the cover 21.

[0059] During inhalation, some air flow may be provided through thenebulizer in a path through the chimney 50. This air flow into thechamber 14 may be provided from ambient in a path provided through theports 72, the chimney inlet 56, the chimney passageway 52, and thechimney outlet 58. This air flow may continue during both inhalationwhen the chimney 50 is in the lower position and exhalation when thechimney is in the higher position. Alternatively, the air flow throughthe chimney 50 may be stopped or reduced during inhalation when thechimney 50 is in the lower position. Control of the airflow through thenebulizer during inhalation or exhalation may be effected by suitableselections of the dimensions of the chimney inlet 56, the chimney outlet58, the actuator ports 72, the diverter ring 82, and other componentsthat affect airflow through the chamber, such as any filters.

[0060] In the embodiment described above, the membrane 64 provides anelastic triggering threshold that permits cyclical nebulization to occurthat coincides with the breathing of the patient. This threshold is setto fall within normal human breathing parameters so that the divertermoves into and out of proximity with the nozzle top as a result of thepatient's normal breathing. In one embodiment, this level may beapproximately less than or equal to 3.0 cm of water. It can beappreciated that the threshold may be established at different levels toaccount for different classes of patients. For example, if the nebulizeris designed to be used with infants or neo-natals, the elastic thresholdof the membrane may be lower than the threshold used for adults.Similarly, a different threshold may be used for geriatric patients. Thenebulizer may be used also for veterinary applications, such as equineor canine. In veterinary applications, there may be a relatively widerange of thresholds related to the various sizes of animals. Nebulizershaving suitably chosen operating thresholds can be designed forveterinary uses. It is also recognized that the openings into thechamber, such as the opening 56, may affect the operating threshold fornebulization. Thus, the operating threshold of the nebulizer may be madereadily adjustable by making the actuator 68 adjustable. Alternatively,the operating threshold may be adjusted by selection of the size of theopenings 56 and 72 into the chamber which would also control airentrainment. This would permit the user to adjust the thresholds, ifdesired. By appropriate adjustment of the operating thresholds, flowcontrol through the nebulizer can be provided. For example, it may bedesirable that the patient not inhale or exhale too quickly or toodeeply. For adults, a suitable flow rate may be approximately 30-60liters/minute. The openings into and out of the chamber may be suitablyadjusted to provide for these rates.

[0061] The nebulizer may be operated manually instead of relying on thebreath-actuated feature. To operate the nebulizer manually, the actuator70 is pressed down toward the cover 21. As mentioned above, the actuator70 is connected to the chimney 50. Pressing the actuator 70 brings thediverter 60 down into the nebulizing position close to the nozzle 24.Release of the actuator 70 causes the chimney 50 to rise due to thebiasing of the membrane 64 thereby causing nebulization to cease.

[0062] Referring to FIGS. 4 and 4A, the indicators 69A and 69B provide aconvenient way to confirm the operation of the nebulizer. As mentionedabove, when the diverter 60 is spaced away from the top of the nozzle24, no aerosol is being generated. When the diverter 60 is spaced awaythe actuator 68, the actuator 68, which is connected to the diverter 60through the chimney 50, is in an upper position and the red indicator69A on the side of the actuator 68 is visible along the top side 21 ofthe nebulizer 10, as shown in FIG. 4. When the patient inhalessufficiently to bring the diverter 60 into a lower position, the redindicator 69A on the side of the actuator 68 is withdrawn through theopening 56 in the top side 21 of the nebulizer 10. The red indicator 69Ais no longer visible, however, the green indicator 69B, which is locatedabove the red indicator 69A, remains visible at the top 21 of thenebulizer. Thus, a patient or medical attendant can readily determinewhether the nebulizer is operating. In embodiments of the nebulizer forchildren, the actuator and/or indicators can be designed with comicfigures.

[0063] The breath actuation of the nebulizer is convenient andefficient. By cycling the nebulization of the liquid, the nebulizer canbe more efficient thereby reducing the cost of the therapy.

[0064] An important advantage follows from the feature of this nebulizerthat nebulization can be cycled so as to occur in coordination with aphysiological cycle of the patient. Specifically, by nebulizing onlyduring an inhalation, for example, the dosage of medication delivered tothe patient can be more accurately delivered and monitored. This enablesthis embodiment of the nebulizer to provide for dosimetric medicationdelivery to an extent that has been otherwise unavailable. By limitingthe medication delivery to the inhalation cycle of the patient, adosimetric portion of the medication can be provided.

[0065] In addition, the nebulizer 10 provides for high output anduniform nebulization due to the arrangement of the gas and liquidorifices 38 and 46 relative to the diverter 60. The annularconfiguration of the liquid orifice 46 relative to the gas orificeprovides for aerosol generation in a approximately 360° direction. Thisenables a relatively high and uniform rate of nebulization. Theuniformity it enhanced because the nebulization is formed with little orno impaction of liquid against the diverter.

[0066] In alternative embodiments of the nebulizer, the cover 12 mayinclude an air filter that covers the air inlet 56. The filter wouldserve to keep contaminants out of the chamber and deter the escape ofnebulized liquid. Such a filter may be removable to permit simple,inexpensive replacement.

[0067] In a still further embodiment, the nebulizer may be used inconjunction with an aerosolization spacer, such as an Aerochamber® soldby Trudell Medical Partnership of London, Ontario. The Aerochamberspacer is described in U.S. Pat. No. 4,470,412, the entire disclosure ofwhich is incorporated by reference herein. In this alternativeembodiment, the output of the nebulizer would be directed into the inletof the Aerochamber from which the patient inhales the aerosol through anoutlet of the Aerochamber.

[0068] Another advantage provided by this embodiment of the nebulizer isthat less aerosol is likely to escape to the surrounding environment.This potentially benefits attending care providers who would otherwisebe exposed to aerosol medication that is released from nebulizers thatgenerate on a continuous basis.

[0069] In a present embodiment, the membrane 64 is biased to keep thechimney in an upper, non-nebulizing position except during inhalation.Thus), in the periods of time between inhalations and exhalations, or ifthe patient pauses and removes the mouthpiece, nebulizing does not takeplace. In alternative embodiments, the membrane 64 may bias the chimneydownward so that the nebulizer generates an aerosol or nebula exceptduring exhalation. This alternative may not be as efficient as the prioralternative, but may still provide significant advantages overnebulizers that generate aerosol continuously.

[0070] In further alternative embodiments of the nebulizer, the gasorifice 38, the gas passageway 34, or a portion thereof, may have ashape that modifies the force of the pressurized gas against thediverter 60. For example, the gas orifice 38 may have a conical shapethat facilitates the change of direction of the gas when it is directedagainst the diverter, so that the force of the gas would not move thediverter away during inhalation thereby helping to direct the gas outinto the chamber. In other embodiments, the conical geometry may bevaried to tailor gas force and flow.

[0071] As mentioned above, the membrane 62 serves as a biasing memberthat moves the diverter. Preferably, the membrane is constructed of asilicone rubber material. Other materials capable of repetitive flexing,compression or expansion in response to the force of inhaled or exhaledair, such as a spring, or elastic bellows, may also be used. The biasingmember is constructed so that it will move the diverter a predetermineddistance away from or toward the nozzle during the course of a patient'sspontaneous or ventilated breathing.

[0072] In a present embodiment, the diverter moves up and down inresponse to the patient's breathing. However, in alternativeembodiments, the nozzle 24 can move instead of the diverter, oralternatively, both the nozzle and the diverter can move. Also, in apresent embodiment, the diverter movement is up and down, but inalternative embodiments, the movement can be side to side, rotating, orpivoting. Alternatively, instead of moving diverter into proximity witha gas outlet, in alternative embodiments, the liquid jet or orifice canbe moved toward the gas jet or orifice, or is otherwise directed towardthe gas jet or orifice, or vice versa. In effect, alternativeembodiments contemplate various means of bringing or diverting the gasand liquid streams into proximity in a cyclical basis.

[0073] In alternative embodiments of the nebulizer, the liquid orificemay have shapes other than annular. For example, the liquid orifice maybe located adjacent to the gas orifice. Alternatively, the liquidorifice may be formed of a series of orifices positioned adjacent orannularly around the gas orifice.

[0074] The nebulizer 10 may also be provided with a plurality of supportlegs (not shown) that are connected around the exterior of the housing12 and provide support therefor.

[0075] In this embodiment, the diverter 50 moves into proximity with thenozzle 24 due to a negative pressure in the chamber 14. However, thepressure variance may also be created by a variance in positivepressure, or a combination of positive and negative pressures.

[0076] II. Second Embodiment

[0077] A second embodiment of a nebulizer is shown in FIG. 5. Accordingto this embodiment, a nebulizer 110 has a housing 112 that defines achamber 114. A lower portion of the chamber 114 serves as a reservoir123 for holding a liquid to be nebulized. Located in a lower portion ofthe housing 112 is a nozzle assembly 124. The nozzle assembly 124 may besimilar or identical to the nozzle assembly of the first embodiment,described above. Like the first embodiment, a bottom of the nozzleassembly 124 has a fitting 128 that can be connected to a supply ofpressured gas 127 by means of conventional tubing 129. Located in thenozzle assembly 124 are inner and outer tubular members that define gasand liquid passageways that exit at gas and liquid orifices at the topof the nozzle assembly 124, as in the first embodiment. Like the firstembodiment, the gas and liquid orifices preferably have a concentricarrangement with the liquid orifice having an annular shape encirclingthe gas outlet orifice. Also, like the first embodiment, in theembodiment of FIG. 5 the reservoir 123 includes a relatively wide, butshallow, primary or upper portion 188 and a relatively narrow, but deep,lower or secondary portion 190.

[0078] Although this embodiment is shown without a bell-shaped bafflesimilar to baffle 74 of the first embodiment, a baffle may be providedin this embodiment. If a baffle were provided in this embodiment, itwould have a construction similar to that of the baffle 74 of FIG. 1.

[0079] In the embodiment of FIG. 5, a chimney 150 is located in an upperportion of the housing 112. The chimney includes a first internalpassageway 152. In this embodiment, the internal passageway 152 of thechimney assembly 150 serves as an outlet 198 from the chamber 114. Theoutlet connects to a mouthpiece 199, or other suitable means ofdelivering an aerosol to a patient, such as a mask. A diverter 160 islocated at and connected to a lower end of the chimney 150. The diverter160 is located a predetermined distance from the top of the nozzleassembly 124. In this embodiment, this distance is approximately 0.033inches. Unlike the first embodiment, the chimney assembly 150 in thisembodiment 110 is not movable between upper and lower positions.Instead, the chimney assembly 150 is fixed in position so that thediverter 160 is maintained a suitable distance from the top of thenozzle assembly 124 to generate an aerosol.

[0080] In this embodiment, at least one second air passageway 153 isprovided. The second air passageway 153 is located adjacent to the firstair passageway 152 in the chimney assembly 150. The second airpassageway 153 communicates with an inlet opening 161 and a suctionchamber 163. The suction chamber 163 is located around a lower end ofthe chimney assembly 150 and specifically, around the perimeter of thediverter 160. An opening 158 communicates between the suction chamber163 and the chamber 114. As pressurized gas and nebulized liquid flowpast the perimeter of the diverter 160, a pressure variance is createdthat draws air from ambient through the inlet opening 161 through thesecond passage way 153 into the suction chamber 163. In one embodiment,the pressure variance is a negative pressure, however, the pressurevariance may also be created by a variance in positive pressure, or acombination of positive and negative pressures. The suction provided atthe opening 158 serves to enhance generation of the aerosol.

[0081] A nebulizing enhancement feature provided by the nebulizer 110relates to the shape of wall 171 around the opening 158. As shown inFIGS. 5 and 6, the shape of the wall 171 includes a first region 173 anda second region 175. The first region 173 is separated from the secondregion 175 by a step or shoulder 177. The first region 173 and thesecond region 175 are preferably horizontal, flat surfaces and theshoulder 177 is preferably a vertical surface. The wall 171 alsoincludes a third region 179. The third region 179 is located around thesecond region 175. The third region 179 is a sloped or angled surfacethat extends from the second region 175 to a gap 186 formed adjacent toa diverting ring 182.

[0082] The shapes of the first, second and third regions 173, 175 and177 affect the air flow in the chamber from the diverter. The relativesizes and shapes may be varied to enhance particle size generation anduniformity. An alternative embodiment of the wall 171 and regions 173,175, and 177 is shown in FIG. 7. In the embodiment of the wall 171Ashown in FIG. 7, the relative sizes of the first region 173A, secondregion 175A, and third region 177A are modified relative to those in theembodiment of FIG. 6. These sizes are varied to affect the size anduniformity of the particle distribution of the nebula or aerosol.

[0083] Referring again to FIG. 5, located in a wall of the chimney 150is at least one, and preferably a plurality of openings 185. Openings185 communicate between the chamber 114 and the first air passageway 152of the chimney assembly 150.

[0084] Referring to FIGS. 5 and 8, a diverting ring 182 may be providedin the chamber 114 to reduce the presence of large droplets and helpmake the aerosol delivered to the patient more uniform. As mentionedabove in connection with the first embodiment, the diverting ringprovides this function, in part, by limiting the migration of dropletson the inside wall of the nebulizer housing. In addition, by forming abarrier on the inside wall of the housing, the diverting ring forces thenebulized aerosol to travel along a relatively non-linear path to movefrom the lower part to the upper part of the chamber and out themouthpiece.

[0085] Referring to FIG. 5, to operate the nebulizer 110, a suitableamount of liquid medicine is placed in reservoir of the chamber 114. Theoutlet 198 is connected to the mouthpiece 199 in a suitable manner. Thesource of pressurized gas 127 is connected to the fitting 128. The flowof gas from the top of the nozzle assembly 124 is directed by thediverter 160 across the annular liquid orifice surrounding the gasorifice causing the generation of an aerosol from the liquid in thereservoir. The aerosol is generated in a 360° direction into the chamber114 around the nozzle 124 and diverter 160.

[0086] An air flow path is established into the chamber 114 from theinlet 161. The gas provided by the source 127 also supplements the airsupply into the chamber 114. Air flows into the chamber through thesecond passageway 153 through the suction chamber 163 and opening 158.Air flow laden with aerosolized liquid from the chamber 114 travels pastthe gap 186, through the opening 185, into the first air passageway 152,and out from the outlet opening 198 to the mouthpiece 199 or face mask.In this embodiment, nebulization may proceed continuously, or may becycled by other means, such as cycling of the gas supply.

[0087] Alternative embodiments of the diverting ring arrangement areshown in FIGS. 9 and 10. In FIG. 9, the diverting ring 182A extendsfurther toward the chimney 150 almost overlapping an edge 183A at thebottom 150A of the chimney 150. This arrangement provides an even moretortuous pathway for the aerosol than the embodiment shown in FIG. 8.The embodiment of FIG. 8 may provide an even more uniform particledistribution. In FIG. 10, the passageway between the diverting ring 182Band the bottom 150B of the chimney is extended thereby providing alonger pathway of a narrow dimension. The embodiment of FIG. 10 mayprovide an even more uniform particle distribution than the embodimentsof FIG. 8 or 9.

[0088] III. Third Embodiment

[0089] A nebulizer 210 according to another embodiment of the inventionis shown in FIGS. 11-13. The nebulizer 210 is similar to the previousembodiments of the nebulizers discussed above. The nebulizer 210includes a housing 212 defining a chamber 214. In the embodiment of FIG.11, the housing 212 is relatively larger than the housings of theprevious embodiments. For example, the housing 212 may have a height ofapproximately 11 cm (4.33 in.) and a diameter of approximately 9 cm(3.54 in.). This enables the nebulizer 210 to hold a correspondinglylarger volume of liquid and aerosol. A large size nebulizer, such asshown in FIG. 11, may be suitable for certain veterinary applicationssuch as for horses, cattle, dogs, etc. A larger size nebulizer may alsobe used with humans for uses such as sputum induction.

[0090] A fitting 238 connects to a pressurized gas supply (not shown)and an outlet 298 provides nebulized medicine from the chamber 214 tothe patient. The outlet 298 may connect to a mouthpiece, mask, orventilator, as appropriate. Like the first described embodiment, thenebulizer 210 has a movable chimney 250. In the chamber 214 of thenebulizer 210, there are a plurality of nozzle assemblies 224A, 224B,and 224C. Each of these nozzle assemblies may be similar to the nozzleassembly 24 of the first embodiment. Each of the nozzle assembliesincludes a gas supply passageway, such as 234A, and an annular liquidsupply passageway, such as 242A. At the top ends of each of the nozzles224A, 224B, and 224C, the gas passageways of each communicate with gasoutlet orifices 238A, 238B, and 238C, respectively and the liquidpassageways of each communicate with liquid outlet orifices 246A, 246B,and 246C. The liquid inlets 244 into each of the nozzles assembliescommunicate in common with a reservoir 223 formed at the bottom of thechamber 214.

[0091] Located at the bottom of chimney is a diverter 260. The diverter260 may be formed of a single face or surface, or may be formed ofmultiple faces or surfaces that are aligned with the multiple nozzleassemblies 224A-224C, or alternatively, the diverter may be formed as aring. Further, there may be provided multiple diverters. In a preferredembodiment, there is a space or gap 261 formed centrally in the bottomof the diverter 260 to permit aerosol generation in 360° around each ofthe nozzles.

[0092] A membrane 264 may be located at the top of the chimney 250 toprovide a biasing function as in the embodiment of FIG. 1. Due to thelarger size and weight of the chimney assembly 250 in the embodiment ofFIG. 11 relative to the embodiment of FIG. 1, a biasing member 265 suchas a spring may be provided in substitution for or in addition to themembrane 264. The spring or other biasing member 265 may be connected tothe top of the chimney assembly 250.

[0093] The nebulizer 210 is operated in a manner similar to thenebulizer shown in FIG. 1. Like the nebulizer shown in FIG. 1, thenebulizer 210 in FIG. 11 is breath- or pressure-actuated. After asuitable liquid is stored in the housing 212, the generation of a nebulaor aerosol will cycle with the cyclic decrease of pressure in thechamber 214. The decrease of pressure may be caused by inhalation by thepatient, or by action of ventilator. As in the first embodiment,nebulization will cease upon exhalation or in the absence of inhalation.

[0094] Because the nebulizer 210 has multiple nozzles 224A-C, a largeamount of liquid can be nebulized quickly. Since the single diverter orconnected multiple diverters move in unison toward the multiple nozzleswith the patient's inhalation, the cycling of nebulization iscoordinated among all the nozzles.

[0095] As in the previous embodiments, the annular shape of each of theliquid orifices provides for a high nebulization generation rate.Although the embodiment of FIGS. 11-13 shows three nozzles, there can beany number of multiple nozzles, such as two, four, five, etc.

[0096] In an alternative embodiment, the diverter 260 is rotatablerelative to the body 252 of the chimney 150. The diverter 260 mayinclude appropriate vanes, channels or a propeller, that captures someof the pressurized gas flow and causes the diverter 260 to rotate insidethe housing 212. Rotation of the diverter 260 may be used to improvemixing of the aerosol inside the chamber.

[0097] This embodiment may also include a bell-shaped baffle as shown inthe first embodiment.

[0098] IV. Fourth Embodiment

[0099]FIG. 14 shows a fourth embodiment of a nebulizer of the presentinvention. This embodiment 310 of the nebulizer is adapted for use witha ventilator circuit 301. The ventilator circuit 301 includes aninspiratory airflow passageway 302 that delivers air from the ventilatorto the patient. This embodiment of the nebulizer 310 is located in theinspiratory airflow passageway 302 connected between a first length ofinspiratory tubing 303 that delivers air from the ventilator circuit 301and a second length 304 that delivers air to the patient. The secondlength of inspiratory tubing 304 may connect to the patient by means ofa mask, endotracheal tube, etc.

[0100] Like the embodiment of FIG. 1, the embodiment of the nebulizer inFIG. 14 is pressure- or breath-actuated. Accordingly, the nebulizer 310produces an aerosol in a cyclical manner in coordination with thebreathing or ventilation of the patient. The nebulizer 310 has a housing312 defining a chamber 314. A nozzle assembly 324 extends up from thebottom of the chamber 314. Pressurized gas is delivered from a gasorifice at the top end of the nozzle assembly 324 and liquid from areservoir 323 at the bottom of the chamber 314 is drawn up to a liquidorifice also located at the top end of the nozzle assembly 324 as in thefirst embodiment. A chimney assembly 350 extends down from a top of thehousing 312. The chimney 350 connects to the housing by means of aflexible, resilient membrane 364. A diverter 360 is located at thebottom of the chimney assembly 350 directly opposite from the gas andliquid orifices at the top of the nozzle assembly 324. An inlet 356 ofthe chimney 350 connects to the length of inspiration tubing 303 fromthe ventilator circuit 301. The inlet 356 communicates with an internalpassageway 352 of the chimney assembly 350. Inspiratory gas from theventilator 301 enters the nebulizer 310 via the chimney inlet 356,passes through the passageway 352 of the chimney assembly 350, andpasses into the nebulizer chamber 314 through the openings 385 locatedin the wall of the chimney 350. The inspired gas exits the nebulizerchamber 314 via an outlet 398. The outlet 398 connects to the secondlength of inspiratory tubing 304 which in turn connects to anendotracheal tube, a mask, or other means (not shown). This embodimentmay also include a bell-shaped baffle as shown in the first embodiment.

[0101] In the embodiment of FIG. 14, the normal operation of theventilator circuit 301 causes a sufficient change in the pressure in thenebulizer 310 to induce the chimney assembly 350 to move into and out ofproximity with the nozzle assembly 324. Accordingly, during aninspiration cycle, the chimney assembly 350, including the diverter 360,will be brought into proximity with the top of the nozzle assembly 324causing nebulization of the liquid (as described above in connectionwith the first embodiment). During an expiratory phase of the ventilator301, the diverter 350 is positioned away from the nozzle assembly 324thereby causing nebulization to stop. Nebulization cycles automaticallyin synchronism with the operation of the ventilator. No extra connectionis required beyond that necessary to withdraw the aerosol from thechamber 314 of the nebulizer 310 into the inspiratory tubing of theventilator circuit.

[0102] V. Fifth Embodiment.

[0103]FIG. 15 shows a fifth embodiment 410 of the nebulizer of thepresent invention. Like the previous embodiment, the nebulizer 410 inFIG. 15 is adapted for use in a ventilator circuit and produces anaerosol in a cyclical manner in coordination with operation of theventilator and/or the breathing of the patient.

[0104] A ventilator circuit 401 has an inspiratory passageway 402 thatis formed of a first length of tubing 403 that connects to theventilator 401 and a second length of tubing 404 that connects to a mask405, or endotracheal tube, and so on, associated with the patient. Theventilator circuit 401 also includes an exhalation valve pressure line406. This exhalation valve pressure line 406 connects to an exhalationvalve 407 associated with an expiratory passageway 408. Duringventilation of the patient, pressured gas is delivered in the exhalationvalve pressure line 406 to the exhalation valve 407 to assist in thecycling of ventilation of the patient.

[0105] The nebulizer 410 has a housing 412 defining a chamber 414, andincludes a nozzle assembly 424, a flexible, resilient membrane 462, anda diverter 460, arranged generally as in the previously describedembodiment. Instead of a chimney, the nebulizer 410 has a post 450 towhich the diverter 460 is connected. Unlike a chimney, the post 450 doesnot include air openings or an internal air passageway. The diverter 460is connected to a bottom side of the post directly adjacent from the topof the nozzle assembly 424. The embodiment of FIG. 15 also differs fromthe previous embodiment in the manner that the ventilator circuit 401 isconnected to the nebulizer 410 and the manner that the ventilatorcircuit 401 causes the nebulizer 410 to cycle nebulization. Thisembodiment may also include a bell-shaped baffle as shown in the firstembodiment.

[0106] In FIG. 15, the nebulizer housing 412 includes an inlet 456 intothe chamber 414. The inlet 456 connects to the first section 403 ofinspiratory tubing 402 from the ventilator circuit 401. The nebulizerhousing 412 also includes an outlet 498 from the chamber 414. The outlet498 connects to the second section 404 of inspiratory tubing that leadsto a conventional device 405, e.g. an endotracheal tube or mask, fromwhich the patient receives the inspiratory flow from the ventilator 401including the aerosol from the nebulizer 410.

[0107] Located across the membrane 462 from the nebulization chamber 414is a passageway 483. The passageway 483 connects to the exhalation valvepressure line 406 of the ventilator circuit 401 by a suitable means,such as a tee 487. Because the ventilator 401 cycles air to and from thepatient, air flows in the exhalation valve pressure line 406 in a cyclicmanner to operate the exhalation valve 407. This air flow in theexhalation valve pressure line 406 causes a pressure differences withthe air in the chamber 414. The membrane 462 is positioned across theinspiratory flow passageway 402 and the exhalation valve pressure line406 and therefore senses the pressure differential across these twopassageways. As in the previous embodiment, the diverter 460 is broughtinto proximity with the top of the nozzle assembly 424 during theinspiratory phase of the ventilator and brought out of proximity withthe top of the nozzle assembly 424 during the expiratory phase of theventilator. Accordingly, nebulization occurs during the inspiratoryphase and not during the expiratory phase.

[0108] VI. Sixth Embodiment.

[0109]FIG. 16 shows a sixth embodiment 510 of the nebulizer of thepresent invention. This embodiment is similar to the embodiment of thenebulizer 110 in FIG. 15. The nebulizer 510 includes a housing 512defining a chamber 514. The chamber 514 has an inlet 528 connected to asource of pressurized gas 527 and an outlet 598 connected to a tubing599, or similar structure, such as a mouthpiece, etc., that leads to thepatient 596 and from which the patient can inhale air and aerosol. Likethe embodiment of FIG. 5, the nebulizer 510 of FIG. 16 may also includean inlet for air entrainment 562. As in the other embodiment, liquid andgas outlets (not shown) located at the top of a nozzle 524 directlyadjacent a diverter 560 dispense an aerosol into the chamber 514.

[0110] The embodiment of the nebulizer 510 includes a breath-actuationfeature that enables the nebulizer to generate a nebula in cyclic mannerin coordination with a physiological cycle of the patient. In theembodiment of FIG. 15, the breath-actuation feature is external of thenebulizer housing 512. The breath-actuation feature includes a valve 569or other metering device located in-line with the inlet tubing 529 thatprovides the pressurized gas from the source 527 to the nebulizer inlet528. A tubing 567 connects from the outlet tubing 599 to the inlettubing 529. The tubing 567 enables the valve 569 to sense the pressurein the outlet tubing 599. In one embodiment, the tubing 567 may beconventional tubing and the valve 569 senses the pressure through thetubing 567. The valve 569 is adapted to open and close the delivery ofpressurized gas to the nebulizer 510 in coordination with the changes inthe pressure in the outlet 599 as sensed via the tubing 567.Specifically, upon inhalation, the pressure in the inlet 599 and theconnecting tubing 567 will be lower, and the valve 569 will open toallow pressurized gas to be delivered to the nebulizer 510 therebycausing nebulization to occur. After inhalation, the pressure in thepatient outlet 599 and the connecting tubing 567 rises, and the valvecloses thereby causing nebulization to cease. In this manner, theembodiment of FIG. 16 can provide similar breath-actuation features asthe other embodiments discussed above. The tubing 567 and valve 569 maybe either re-usable or disposable and may be used with a nebulizer 510as shown in FIG. 16, or may be used with other types of nebulizers. Thetubing 567 and valve 569 could also be used with vaporizers that areused for providing humidification for ventilated patients. Suchvaporizers are used with prefilled bags of sterilized water, and thetubing 567 and valve 569 would provide adjustable air entrainment ofvapor.

[0111] VII. Seventh Embodiment.

[0112]FIGS. 17A and 17B show a seventh embodiment 610 of the nebulizerof the present invention. This embodiment is similar to the previousembodiments wherein a housing 612 defines a chamber 614 for holding andaerosolizing a liquid 625 by means of a pressured gas supply 627. Inthis embodiment, a top end of a diverter assembly post 650 is connectedto the top side of the housing so that the bottom surface 660 of thediverter post 650 is located at a fixed distance, e.g. 0.033 inches,from a top 639 of a nozzle assembly 624. As in the previous embodiments,a gas orifice and a liquid orifice (not shown) are located at the top ofthe nozzle assembly 624. The liquid orifice may be ring-shaped andconcentric with the gas orifice, or alternatively, the orifices may beside by side. A mouthpiece 700 permits the withdrawal of aerosol and airfrom the chamber 614. A flexible diaphragm 664 is located in an upperregion of the nebulizer chamber 614 and forms a boundary between theinside of the chamber and the ambient outside. One or more air inletports 656 are located on a top side of the housing 612. A filter 639 islocated at the top of the diverter post 650.

[0113] A cylindrical shield or collecting surface 633 is connected tothe flexible diaphragm 664 and extends downward into the chamber 614over the lower portion of the diverter post 650 and the upper portion ofthe nozzle assembly 624. The shield 633 has an inside diameter largerthan the outside diameters of the diverter post 650 and the nozzleassembly 624 so that it can readily shift relative to these parts. Oneor more windows 637 are located in the wall of the shield 633. Thewindows 637 are located in the wall of the cylindrical shield 633 suchthat when the diaphragm 664 is in an upper position (as shown in FIG.17B) the window 637 is not aligned with the gap between nozzle 624 andthe diverter 660. When the shield 633 is in this upper position, aerosolparticles generated by the flow of pressured gas across the liquidorifice impact upon the inside wall of the cylindrical shield 633 andtend to form into droplets that fall back into the reservoir. Inaddition or alternatively, depending on the specific dimensions, theshield 633 may impede the flow of gas from the pressurized gas orificeacross the liquid orifice to the extent that there is insufficientvacuum to draw the liquid out of the liquid orifice. In any event, theproduction of aerosol particles into the chamber 614 is reduced.However, when air is withdrawn from the chamber 614, such as when apatient inhales through the mouthpiece 700, a decrease in pressureinside the chamber 614 causes the diaphragm 664 to flex downward (asshown in FIG. 17A). This causes the cylindrical shield 633 to shift intoa lower position. When the shield 633 is in a lower position, the window637 is aligned with the gap between the nozzle 624 and the diverter 660thereby permitting aerosol generated from the liquid orifice to escapeinto the chamber 614 from which it can be inhaled by the patient.

[0114] The above embodiments of the nebulizer have been described foruse in medical or therapeutic applications. It is noted that theprinciples of the invention disclosed herein may have applicability toother usages, such as industrial, manufacturing, or automotive (e.g.carburetors).

[0115] It is intended that the foregoing detailed description beregarded as illustrative rather than limiting, and that it be understoodthat the following claims, including all equivalents, are intended todefine the scope of this invention.

We claim:
 1. A nebulizer comprising: a housing having a chamber forholding an aerosol; an air outlet communicating with the chamber; aliquid outlet located in the chamber; a pressurized gas outlet locatedin the chamber adjacent to the liquid outlet; a diverter located in thechamber in a fixed position relative to the pressurized gas outlet andthe liquid outlet so as to divert pressurized gas from the gas outletacross the liquid outlet to aerosolize liquid from the liquid outlet;and a shield positioned in the chamber, the shield movable incoordination with a patient's breathing.
 2. The nebulizer of claim 1wherein the shield substantially prevents escape of the aerosol duringthe patient's exhalation.
 3. The nebulizer of claim 1 wherein the shieldsubstantially prevents generation of a vacuum across the liquid outletsuch that substantially no liquid is drawn from the liquid outlet. 4.The nebulizer of claim 1 further comprising a biasing member connectedto the shield.
 5. The invention of claim 4 wherein the biasing membercomprises a flexible membrane.
 6. The invention of claim 4 wherein thebiasing member comprises a spring.
 7. The invention of claim 1 whereinthe nebulizer comprises multiple liquid outlets located in the chamber.8. The invention of claim 1 further comprising an air inletcommunicating with ambient air connected to an air outlet located in thechamber.
 9. The invention of claim 1 comprising a suction chambercommunicating with the chamber.
 10. The invention of claim 1 furthercomprising a means for limiting movement of the shield.
 11. Theinvention of claim 1 wherein during an inhalation, the shield is movedrelative to the gas outlet and gas diverter and forms an opening suchthat the aerosol may escape into the chamber.
 12. The nebulizer of claim1 wherein the shield is movable into an aerosol blocking positionadjacent the gas outlet.
 13. The invention of claim 1 wherein the liquidoutlet has an annular shape surrounding the gas outlet.
 14. Theinvention of claim 1 further comprising: a ventilator circuit; andwherein the chamber connects to the ventilator circuit to deliver theaerosol thereto.
 15. The invention of claim 1 further comprising: aventilator circuit; and wherein the air outlet connects to aninspiratory portion of the ventilator circuit.
 16. The invention ofclaim 1 further comprising: a ventilator circuit; and wherein thehousing includes: an air inlet into the chamber; wherein the air inletconnects to an inspiratory portion of the ventilator circuit to receiveairflow therefrom; and wherein the air outlet connects to a patient. 17.The invention of claim 1 further comprising: a ventilator circuitincluding an inspiratory portion and an expiratory portion; and whereinthe shield is connected to the expiratory portion.
 18. The invention ofclaim 1 further comprising: a ventilator circuit including aninspiratory portion and an expiratory portion; and wherein the shield isconnected to said inspiratory portion.
 19. The invention of claim 1further comprising: a ventilator circuit including an inspiratoryportion and an expiratory portion; and wherein the shield is connectedto both the inspiratory portion and the expiratory portion.
 20. Theinvention of claim 1 further comprising: a mouthpiece; and wherein theair outlet connects to the mouthpiece.
 21. The invention of claim 1further comprising indicator means associated with the shield to providea confirmation of operation.
 22. The invention of claim 21 wherein theindicator means further comprises a pair of colored markings visible onan outside portion of the nebulizer.
 23. The invention of claim 1further comprising a spacer having an inlet connected to the air outlet.24. The invention of claim 1 further comprising a liquid reservoir inliquid communication with the liquid outlet.
 25. A method of supplyingnebulized medication to a patient comprising the steps of: providing anebulizer having an outlet for delivery to a patient, a chamber, abiasing member attached to the chamber, a gas diverter fixedlypositioned relative to a pressurized gas nozzle in the chamber, and amovable shield attached to the biasing member inside the chamber;inhaling air from the chamber through the patient outlet; moving thebiasing member with the force of the inhaled air, the biasing membermoving the movable shield from an initial position adjacent at least aportion of at least one of the pressurized gas outlet and the gasdiverter to a second position relative to the pressurized gas outlet,wherein the movable shield moves between the initial position and thesecond position in coordination with the patient's breathing.
 26. Themethod of claim 25 further comprising the steps of: exhaling into thenebulizer through the air outlet; and blocking the nebulized medicationwith the movable shield so that substantially no nebulized medicationescapes into the chamber.
 27. The method of claim 25 further comprising:exhaling into the nebulizer through the air outlet; and impeding a flowof gas from the pressurized gas nozzle with the movable shield to atleast substantially prevent generation of nebulized medication.
 28. Themethod of claim 26 wherein the step of blocking the nebulized medicationcomprises unflexing the membrane with the force of the exhaled air andmoving the movable shield to the initial position.
 29. The method ofclaim 25 wherein the medication avoids substantially impacting a surfaceafter being drawn from the liquid outlet during inhalation.
 30. Themethod of claim 25 wherein a substantially constant flow of pressurizedgas is supplied through the pressurized gas outlet.